Initial Surfactant Concentration Research Articles

Investigating the removal of linear alkyl benzene sulfonate from aqueous solution by ultraviolet irradiation and hydrogen peroxide process

This study investigated the efficiency of ultraviolet radiation and hydrogen peroxide for the removal of linear alkylbenzene sulfonate (LAS) from aqueous solutions. Methylene blue active substances assay and spectrophotometry were used to determine the amount of anionic and residual surfactants. The effect of H2O2 concentration, initial concentration of surfactant, pH, and length of UV radiation were examined. The potential for use of UV/H2O2 to degrade LAS was analyzed statistically using multiple linear regression analysis. The results showed that after 20 min of contact time, ultraviolet radiation alone removed 38.44% of the LAS. The use of hydrogen peroxide alone for 10, 20, and 30 min showed no effect on the removal of LAS. The removal rates for the combination UV/H2O2 at 10, 20, and 30 min were 86.2, 90, and 96.5%, respectively. The results of this study showed that the use of ultraviolet radiation and hydrogen peroxide individually for degradation of anionic surfactant was not effective, but the combination of UV/H2O2 was effective for the removal of anionic detergents.

Removal of direct Yellow 27 dye using animal fat and vegetable oil-based surfactant

The textile industry uses large amounts of water in its processes. Such water ends up contaminated by a number of substances, including dyes, creating an environmental challenge. The present study aims at removing dye by applying the precipitation process using a sodium soap (anionic surfactant), derived from animal fat and vegetable oil, promoting dye decontamination using biodegradable materials. Sodium soap, in the presence of calcium ions, forms another insoluble surfactant. This new surfactant, under stirring, aggregates and forms hydrophobic flocs that are capable of adsorbing organic materials dissolved in aqueous solutions, including dyes. Dye removal was assessed considering the influence of initial surfactant concentration, temperature, pH, presence of electrolyte, equilibrium time, and stirring rate. Dye removal efficiency reached 97.6%.

Synthesis and physicochemical characterization of ZnMgNiAl-CO3-layered double hydroxide and evaluation of its sodium dodecylbenzenesulfonate removal efficiency

In this study, the adsorption of anionic surfactant by uncalcined ZnMgNiAl-CO3 was examined using sodium dodecylbenzenesulfonate (SDBS) as a model compound in an aqueous solution. The synthesized adsorbent (ZnMgNiAl-CO3) was characterized by FTIR, X-ray diffraction, and BET. The capacity of ZnMgNiAl-CO3 to adsorb surfactant was evaluated at different contact times, pH values, mass effect, and initial surfactant concentrations. According to the obtained results, the adsorption processes could be described by a pseudo-second-order kinetic model. The adsorption isotherm was well fitted by the Sips model. Maximum adsorption capacity for SDBS on ZnMgNiAl-CO3 was found to be 191.7 mg/g which was in accordance with the experimental value. Thermodynamic parameters were estimated as well, and their values indicated that the adsorption process was spontaneous and endothermic. The values of ΔH° and ΔS° of the adsorption process were 7.9 and 0.102 kJ/mol, respectively. The low value of ΔH° (<40 kJ/mol) indicated that adsorption process occurs mainly through a physical means.

Synthesized of nanophotocatalyst ZnO and ZnO doped with SnO2 and their application photochemical degradation a surfactant in aqueous solutions

In this paper, we synthesized of pure ZnO and ZnO doped with SnO2 nanophotocatalyst by sol gel method. The successful synthesis of ZnO nanopowders was evident by XRD lines. Furthermore SnO2 were well incorporated into the ZnO crystal lattice in doped sample. Scanning electron microscope (SEM) analysis revealed that the SnO2 were well incorporated into the ZnO crystal lattice. The photocatalytic activities of these materials were investigated for Sodium alkyl benzene sulfonate removal from aqueous solution under UV light irradiation. It was shown that the use of ZnO/SnO2 as photocatalyst have better photocatalytic activity for degradation of Sodium alkyl benzene sulfonate than ZnO. The effects of initial concentration of surfactant, catalyst loading, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined.

Effects of surfactants on rheological properties of a dispersed viscoelastic microsphere

ABSTRACTThe swelling ratio is an important performance for the application of viscoelastic microsphere. The reduction of swelling ratio can affect the particle size. The compatibility between particle size and formation pore can affect the plugging performance and EOR capability. Adsorption characteristics of cationic surfactant cetyltriethylammnonium bromide (CTAB), anionic surfactant petroleum sulfonate applied in GangXi oilfield (GXPS), and nonionic surfactant nonylphenol ether (TX‐10) onto viscoelastic microspheres and the effect of the three types of surfactant on swelling ratio of viscoelastic microspheres were investigated. Effects of surfactants on rheological properties of viscoelastic microspheres were researched in two different modes referring to steady shear and dynamic shear, respectively, using Physica MCR301 Rheometer. The results showed that the interactions between viscoelastic microsphere and surfactants CTAB were electrostatic attraction and hydrophobic association, that the interaction between viscoelastic microsphere and surfactants TX‐10 was just hydrophobic association, and that the interactions between viscoelastic microsphere and GXPS were electrostatic repulsion and hydrophobic association. At the same initial surfactant concentration, all these three types of surfactant could be adsorbed onto the surface of viscoelastic microspheres and reduce its swelling ratio and storage modulus. Because of different amount of adsorption, the extent of reduction order on swelling ratio and storage modulus was CTAB&gt;TX‐10&gt;GXPS. In addition, the yield stress of viscoelastic microspheres which was obtained from modeling the data to Herschel‐Bulkley model decreases with the increase of surfactant adsorption. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42278.

Caffeic Acid Phenethyl Ester Loaded PLGA Nanoparticles: Effect of Various Process Parameters on Reaction Yield, Encapsulation Efficiency, and Particle Size

CAPE loaded PLGA nanoparticles were prepared using the oil in water (o/w) single emulsion solvent evaporation methods. Five different processing parameters including initial CAPE amount, initial PLGA amount, PVA concentration in aqueous phase, PVA volume, and solvent type were screened systematically to improve encapsulation of hydrophobic CAPE molecule, simultaneously minimize particle size, and raise the reaction yield. Obtained results showed that the encapsulation efficiency of the nanoparticles significantly increased with the increase of the initial CAPE amount (p &lt; 0.05) and particle size (p &lt; 0.05). Furthermore, the particle size is significantly influenced by initial polymer amount (p &lt; 0.05) and surfactant concentration (p &lt; 0.05). By the optimization of process parameters, the nanoparticles produced 70 ± 6% reaction yield, 89 ± 3% encapsulation efficiency, −34.4 ± 2.5 mV zeta potential, and 163 ± 2 nm particle size with low polydispersity index 0.119 ± 0.002. The particle size and surface morphology of optimized nanoparticles were studied and analyses showed that the nanoparticles have uniform size distribution, smooth surface, and spherical shape. Lyophilized nanoparticles with different CAPE and PLGA concentration in formulation were examined for in vitro release at physiological pH. Interestingly, the optimized nanoparticles showed a high (83.08%) and sustained CAPE release (lasting for 16 days) compared to nonoptimized nanoparticle.

Simulations of surfactant effects on the dynamics of coalescing drops and bubbles

We present simulations of coalescence in the presence of surfactant. We consider a fluid-fluid interface where we track surfactant concentration. Our model is applicable to a soap bubble merging with a suspended soap film and to a surfactant covered liquid drop merging with a reservoir. In both cases, we determine the regime in which coalescence is only partial. Along with viscous effects, represented by the Ohnesorge number, the elasticity of the surface tension relative to the surfactant concentration is seen to play a key role and exhibits a surprising nonmonotonic influence, for which we present a physical mechanism. The effects of gravity are also simulated, along with effects of differing initial conditions, as well as those of uneven initial surfactant concentration, as are likely to arise in physical applications. We describe how the presence of surfactants can influence a coalescence cascade.

Photo Catalytic Removal of Sodium Dodecyl Sulfate From Aquatic Solutions With Prepared ZnO Nanocrystals and UV Irradiation

In this study, ZnO Nano catalyst has been synthesized and examined as photo catalyst for UV-induced removal of Sodium Dodecyl Sulfate (SDS) from aquatic solutions. This anionic surfactant was selected based upon its toxicity, wide use in industrial laundry and as a primary pollutant in municipal waste water systems.This study aimed to investigate removal of surfactant, SDS, in a batch photo catalytic reactor under various operating conditions including ZnO suspension concentration, initial surfactant concentration and initial pH of solution to find out the desired condition for removal of surfactant. ZnO Nano crystals were synthesized using the precipitation method and ZnSO4.7H2O was used as the starting material and NaOH as precipitant. The removal of SDS reactions by UV/ZnO process was performed into a batch photo reactor. In addition, various operating conditions including ZnO suspension concentration, initial surfactant concentration and initial pH of solution were investigated. In total, 98% of surfactant was removed at 40 minute and removal efficiency of SDS increased with increasing pH up to nine and after that with increase in pH, efficiency decreased. Possible roles of inorganic oxidant on the reaction were discussed. The removal of SDS follows pseudo-first order kinetics. Based on the results of this study, ZnO-UV photo catalytic process can be used as an efficient method for further study in detergents removal.

EFFECT OF TWO-DIMENSIONAL MICROPILLAR ARRAYED TOPOGRAPHY ON SPREADING OF INSOLUBLE SURFACTANT-LADEN DROPLET

For the spreading of liquid droplet containing insoluble surfactant over two-dimensional micropillar-arrayed surface, the lubrication theory was adopted to derive the evolution equations of liquid film thickness and interfacial surfactant concentration, and then the droplet spreading characteristics and the effects of related parameters were numerically simulated. Results show that when the surfactant-laden droplet was spreading over micropillar-arrayed surface, the depression appears at the groove while the ridge is shaped at the bump, and the ridge and the depression move towards both sides gradually, and the numbers of ridge and depression increase. Furthermore, when the surfactant film is flowing over the bump, the height of the ridge presents a hump shape. The numbers of ridges and depressions in the spreading region increase and the droplet spreading velocity accelerates with the improved preset film thickness and initial surfactant concentration. Increasing the groove depth or decreasing the steepness can enhance the capillary force effects, resulting in suffering the rupture possibility of the film. Improving the groove width enlarges the film deformation and promotes the film flow.

Adsorption of a cationic surfactant by a magsorbent based on magnetic alginate beads

Adsorption of cetylpyridinium chloride (CPC), a cationic surfactant, by magnetic alginate beads (MagAlgbeads) was investigated. The magnetic adsorbent (called magsorbent) was prepared by encapsulation of magnetic functionalized nanoparticles in an alginate gel. The influence on CPC adsorption of several parameters such as contact time, pH and initial surfactant concentration was studied. The equilibrium isotherm shows that adsorption occurs through both electrostatic interactions with charge neutralization of the carboxylate groups of the beads and hydrophobic interactions inducing the formation of surfactant aggregates in the beads. The dosage of calcium ions released in the solution turns out to be a useful tool for understanding the adsorption mechanisms. Adsorption is accompanied by a shrinking of the beads that corresponds to a 45% reduction of the volume. Adsorption kinetic experiments show that equilibrium time is strongly dependent on the surfactant concentration, which monitors the nature of the interactions. On the other hand, since the pH affects the ionization state of adsorption sites, adsorption depends on the pH solution, maximum adsorption being obtained in a large pH range (3.2–12) in agreement with the pKa value of alginate (pKa=3.4–4.2). Finally, due to the formation of micelle-like surfactants aggregates in the magnetic alginate beads, they could be used as a new efficient magsorbent for hydrophobic pollutants.

DETERMINATION OF METHYLENE BLUE BIOSORPTION BY Rhizopus arrhizus IN THE PRESENCE OF SURFACTANTS WITH DIFFERENT CHEMICAL STRUCTURES

Methylene blue (MB) biosorption properties of Rhizopus arrhizus were investigated in the presence of surfactants. The effects of cationic and anionic surfactants on MB removal by dead biomass (1 g L−1) were determined. MB removal was tested as a function of initial pH (2–12), contact time (5–1440 min), and dye (37.4–944.7 mg L−1) and surfactant (0–10 mM) concentrations. The opposite charged anionic surfactant dodecylbenzenesulfonic acid sodium salt (DBS) enhanced sorption of cationic MB by biomass dramatically. Maximum biosorption capacity was 471.5 mg g−1 at pH 8 with 0.5 mM DBS at 944.7 mg L−1 MB concentration. The surfactant-stimulated fungal decolorization method may provide a highly efficient, inexpensive, and time-saving procedure in biological wastewater treatment technologies.

Surfactant Recovery by Foam Fractionation using the Gas-Liquid Contactor, Emulsion Venturi

Sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, was removed from its aqueous solution by foam fractionation in an emulsion venturi, a gas-liquid contactor functioning in self-aspiration. The performance of the reactor was evaluated by measuring the self-aspired gas flow and the mass transfer coefficient in the presence and the absence of SDBS. Data confirmed that both the gas flow self-aspired and the mass transfer coefficient increased with increasing the recirculated liquid flow. However, the presence of SDBS decreased the mass transfer capacity of the reactor influencing self-aspiration capacity in a positive manner. The percentage removal of SDBS in the emulsion venturi increased with increasing the recirculated liquid flow; at the highest liquid flow value used in this work (1.4 m3/h), 96% of SDBS was removed from the solution after 20 min of foam operating. The process was dependant on initial surfactant concentration. Neutral pH and temperature of 25°C were the optimal conditions for the foam separation of SDBS in the emulsion venturi.

Role of Chain Length and Type on the Adsorption Behavior of Cationic Surfactants and the Silica Floatability

In this study, we investigated the adsorption isotherms of cationic surfactants (i.e., distearyl dimethyl ammonium chloride (DDAC), behenyl trimethyl ammonium chloride (BTAC), and stearyl trimethyl ammonium chloride (STAC)) onto silica surface and the corresponding silica floatability according to chain type and length of cationic surfactants. The results for the adsorption isotherms of cationic surfactants showed that the adsorptive amounts increased with increasing surfactant concentration, but differences in the position of the adsorption isotherms existed between DDAC, BTAC, and STAC. Specifically, in the high range of initial surfactant concentrations (i.e., 10 ¹5 ­10 ¹3 M), the adsorptive amounts increased with increasing hydrocarbon chain length. In addition, in the presence of DDAC, the adsorptive amounts were much greater than those in the presence of BTAC and STAC. The results were attributed to the fact that the increase in the hydrocarbon chain group of surfactants decreased the Gibbs free energy of the system, resulting in a shift of hemimicelle concentration toward lower concentration. Meanwhile, in the low range of initial surfactant concentrations (i.e., 5 © 10¹7­5 © 10¹6M), the adsorptive amounts were comparable regardless of surfactant type, which was due to the fact that the interaction between the cationic surfactants and the silica surface was mainly governed by electrostatic attractive force. The results from silica flotation and hydrophobicity tests showed that silica floatability increased with increasing hydrocarbon chain group of surfactants (i.e., floatability was in the order of DDAC > BTAC > STAC) under the conditions where the adsorptive amounts of the surfactants were comparable and that floatability results were consistent with those for the hydrophobicity of silica surface. Overall, the findings from the present study suggested that the hydrocarbon chain length and type of cationic surfactants play a significant role in both the adsorption behavior of surfactants and the silica floatability. [doi:10.2320/matertrans.M2014088]

Heterogeneous Photocatalytic Degradation of Triton X-100 in Aqueous TiO2 Suspensions

The increasing utilization of surfactants generates a great amount of wastes. Surfactants and their more toxic degradation by-products in the environment affect the biota greatly. In particular, the low biodegradation of nonionic surfactants requires efficient oxidation treatments. In addition, the extracted contaminants by high concentrations of non-ionic surfactants in soil remediation may be completely treated using advanced oxidation process and thus the degradation of non-ionic surfactants needs to be checked in this case. The photocatalytic degradation of Triton X-100, a non-ionic surfactant, in aqueous titania suspensions was investigated as a function of catalyst dosage, pH, addition of hydrogen peroxide, potassium persulfate, and Tert-butyl alcohol. For the treatment of 20 mg/L Triton X-100 solutions, the optimum catalyst dosage and pH were determined to be 1 g/L and 6, respectively. The degradation efficiency of Triton X-100 by potassium persulfate was higher than that by hydrogen peroxide when the same mol of oxidants were used. Tert-butyl alcohol can strongly inhibit the photocatalytic oxidation reactions of Triton X-100. The degradation rates as a function of initial surfactant concentrations were interpreted by using a Langmuir-Hinshelwood model. With 0.2 g/L titania or even an additional 0.1 g/L hydrogen peroxide to completely degrade 1 mg/L phenanthrene in a 2 g/L Triton X-100 solution within 30 min, in this case the degradation efficiency of Triton X-100 was less than 5%. This proved that the strategy that surfactants were used as solubilizing agents for the removal of contaminants from soils followed by heterogeneous photocatalytic degradation was feasible.Within 120 min, 2 g/L of Triton X-100 can be degraded up to 67% by the addition of both 1 g/L titania and 1 g/L hydrogen peroxide. Under the right conditions, Triton X-100 can be completely degraded.

Experimental Characterization of Front Propagation by Marangoni Forces in Ultrathin Liquid Films

Italian physicist Carlo Marangoni published a treatise in 1865 which first described the spontaneous flow of a liquid film caused by gradients in surface t ension at a gas/liquid interface. Such gradients are established by variations in surface concentration of molecular species which lower the surface tension in proportion to the interface concentration. While the dynamics and power law behavior of the initial circular advancing front in surfactant coated films has been studied for about two decades, there has been relatively little work conducted on characterizing the fractal spreading patterns which develop behind this front. In this thesis, we examine the dynamics of front propagation and subsequent fractal evolution in ultrathin liquid films of glycerol driven to spread by concentration gradients in Aerosol OT, an insoluble anionic surfactant. We vary only the initial deposition volume and concentration while maintaining the initial liquid film thickness at 2.5 microns. Contrary to theoretical analyses in the literature, our results reveal that the coefficient and exponent characterizing the advance of both the first front as well as the following unstable front is not a constant depending only on geometry (i.e. rectilinear vs axisymmetric spreading) but varies with the initial surfactant concentration of the deposition volume. Furthermore, the overall speed of the fronts is observed to increase with ambient relative humidity, an effect we ascribe to a reduction in the viscosity of the glycerol film clue to absorption of water from the ambient atmosphere. Only in cases of relatively high humidity (higher than approximately 40% relative humidity) do we observe the formation of fractal patterns in the unstable front. Measurements of the fractal dimension yield values in the range 1.45-1.65. The largest values approximate those fractal dimensions observed in systems undergoing diffusion driven aggregation or viscous fingering, neither of which mechanism is pertinent to Marangoni flow.

Adsorption of fluoranthene in surfactant solution on activated carbon: equilibrium, thermodynamic, kinetic studies

Adsorption of fluoranthene (FLA) in surfactant solution on activated carbon (AC) was investigated. Isotherm, thermodynamic, and kinetic attributes of FLA adsorption in the presence of the surfactant on AC were studied. Effects of AC dosage, initial concentration of TX100, initial concentration of FLA, and addition of fulvic acid on adsorption were studied. The experimental data of both TX100 and FLA fitted the Langmuir isotherm model and the pseudo-second-order kinetic model well. Positive enthalpy showed that adsorption of FLA on AC was endothermic. The efficiency of selective FLA removal generally increased with increasing initial surfactant concentration and decreasing fulvic acid concentration. The surface chemistry of AC may determine the removal of polycyclic aromatic hydrocarbons. The adsorption process may be controlled by the hydrophobic interaction between AC and the adsorbate. The microwave irradiation of AC may be a feasible method to reduce the cost of AC through its regeneration.

Electro-Fenton degradation of anionic surfactants

The degradation of sodium dodecyl benzene sulfonate (LAS), a common industrial and household anionic surfactant, has been investigated by electro-Fenton process at constant current. The electrolyses have been performed using an undivided cell equipped with a Ti/RuO2 anode and a commercial graphite-felt to electrogenerate in situ hydrogen peroxide and regenerate ferrous ions as catalyst. The effect of operating conditions such as applied current, catalyst concentration, initial surfactant concentration and initial pH has been studied. Surfactant decay kinetic was monitored during the electrolysis by UV–vis measurements.The experimental results showed that LAS was completely removed by the reaction with OH radicals generated from electrochemically assisted Fenton’s reaction, and the decay kinetics always follow a pseudo-first-order reaction. With our cell design, the higher oxidation rate has been obtained applying a current of 200mA, at pH 3 and in the presence of 0.3mM Fe2+ as catalyst. In these conditions, after 180min of electrolysis almost complete oxidation of 50mgdm−3 of LAS has been obtained with a specific energy consumption of 9.53±0.5kWhm−3.

Anionic Surfactant Adsorption through Porous Media in Carbonate Cores: An Experimental Study

The phenomenon of surfactant adsorption at solid/liquid interface is of major importance in the process of enhanced oil recovery. The basic objective of this study is to calculate adsorption density and also to model the kinetics of adsorption processes on carbonate rocks. The kinetics adsorption was calculated by examining adsorption behavior in a system of a solid phase (carbonate rock) and an aqueous phase of surfactant with 5,000 ppm synthetic/field brine. The surfactant adsorption on reservoir carbonate rocks was measured to determine the amount of excess surfactant that must be added into the injection stream in the surfactant alternating CO2 injection tests. The adsorption densities were measured by using circulation tests through core samples. The range of initial surfactant concentrations were 500, 1,000, 2,000, and 5,000 ppm in a circulating system. The applied commercial surfactant is sodium lauryl sulphate, which is an anionic surfactant. Finally, the Langmuir adsorption isotherm was used to characterize the equilibria between the amount of adsorbate that accumulates on the adsorbent and the concentration of the dissolved adsorbate. The adsorption process showed that the rate of adsorption is dependent on availability of surfactant in the system. It was found that the adsorption of surfactant increased with increasing surfactant concentration. Also, for the flow-through tests, the necessary equilibrium time was approximately 4 days.

Numerical Investigation of Thin Film Spreading Driven by Surfactant Using Upwind Schemes

Numerical solutions of a coupled system of nonlinear partial differential equations modelling the effects of surfactant on the spreading of a thin film on a horizontal substrate are investigated. A CFL condition is obtained from a von Neumann stability analysis of a linearised system of equations. Numerical solutions obtained from a Roe upwind scheme with a third-order TVD Runge-Kutta approximation to the time derivative are compared to solutions obtained with a Roe-Sweby scheme coupled to a minmod limiter and a TVD approximation to the time derivative. Results from both of these schemes are compared to a Roe upwind scheme and a BDF approximation to the time derivative. In all three cases high-order approximations to the spatial derivatives are employed on the interior points of the spatial domain. The Roe-BDF scheme is shown to be an efficient numerical scheme for capturing sharp changes in gradient in the free surface profile and surfactant concentration. Numerical simulations of an initial exponential free surface profile coupled with initial surfactant concentrations for both exogenous and endogenous surfactants are considered.

Removal of anionic surfactant sodium dodecyl sulphate from aqueous solution by adsorption onto pine cone biomass of Pinus Radiate: equilibrium, thermodynamic, kinetics, mechanism and process design

Abstract This study was undertaken to evaluate the adsorption potential of a natural, low-cost agricultural by-product adsorbent, Pine cone (Pinus Radiate), to remove sodium dodecylsulfate (SDS) from aqueous solution. It was found that the extent of SDS adsorption by pine cone biomass increased with initial surfactant concentration and contact time but decreased with increasing solution pH, amount of adsorbent, and temperature of the system. These studies also suggested that the electrostatic forces and surfactant self-assembly are dominant mechanisms governing this pH dependent adsorption process. Overall, kinetic studies showed that the surfactant adsorption process followed pseudo-second-order kinetics based on pseudo-first-order and intraparticle diffusion models. The different kinetic parameters including rate constant, half adsorption time, and diffusion coefficient were determined at different physicochemical conditions. Equilibrium data were fitted by both the Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine cone biomass was 95.75 mg g−1 at 20°C. The value of separation factor, R L from Langmuir equation and “n” from Freundlich also indicated favourable adsorption. Thermodynamic parameters such as ΔG 0, ΔH 0, and ΔS 0 were calculated. A single-stage batch absorber design for the SDS adsorption onto pine cone biomass also presented based on the Freundlich isotherm model equation.